Commercially available folding knives are typically composed of a handle and a blade, wherein the blade is pivotally connected to the handle and can be rotated about the pivot joint in order to spin out of or be stored in the handle. Compact when folded up, this type of knives can be carried around with ease, and with the blade stored in the handle for enhanced safety. For those engaged in outdoor activities (e.g., divers), soldiers, the police, and so forth, folding knives are far more convenient than knives that are not foldable.
Generally speaking, a folding knife that has been used for quite a while tends to have dirt stuck in the handle as well as a blunt blade. To get rid of the dirt or detach the blade for sharpening. the folding knife must be disassembled. However, folding knives are rarely designed to be taken apart by their users. A folding knife is usually designed in such a way that the blade is pivotally connected between two plates, and that the plates are fastened together with screws or other elements to form the handle and to ensure stability of the folding knife during use. Indeed, such a design can prevent separation of the handle and the blade while the folding knife is being operated, but the same design also adds to the difficulty of disassembly and thus hinders maintenance of the folding knife.
To solve the aforesaid problem, many a structural improvement has been made to the conventional folding knives, as briefly described below. Referring to FIGS. 1A-1D, the folding knife 1 is composed of two plates 11A, 11B; a blade 13; and an actuating portion 15. One side of the plate 11A is protrudingly provided with a pivotal connection post 111 at a position adjacent to one end of the plate 11A. The pivotal connection post 111 is provided with a first block 113 on the top side. The portion between the first block 113 and the pivotal connection post 111 is reduced in diameter to form an engaging groove 1111. The first block 113 is rectangular and is arranged in a tilted manner (see FIG. 1C). The blade 13 is formed with a pivotal connection hole 131 at a position adjacent to one end of the blade 13. The pivotal connection post 111 extends into the pivotal connection hole 131 so that the blade 13 is rotatable about an axis defined by the pivotal connection post 111. The actuating portion 15 has one end pivotally provided on the aforesaid side of the plate 11A at a position adjacent to the opposite end of the plate 11A. Moreover, the top side of the actuating portion 15 is protrudingly provided with a second block 151 at a position adjacent to the aforesaid end of the actuating portion 15. The second block 151 is also rectangular and can rotate along with the actuating portion 15, and the portion between the second block 151 and the actuating portion 15 is also reduced in diameter to form an engaging groove. The plate 11B is formed with a first aperture 112 at a position adjacent to one end of the plate 11B and a second aperture 114 at a position adjacent to the opposite end of the plate 11B. The first aperture 112 and the second aperture 114 are both rectangular. In addition. the first aperture 112 matches the first block 113 in configuration, and the second aperture 114 matches the second block 151 in configuration. The inner wall portion of the plate 11B that corresponds to the bottom of the first aperture 112 is protrudingly provided with an engaging block 1121, and the inner wall portion of the plate 11B that corresponds to the bottom of the second aperture 114 is protrudingly provided with another engaging block.
With continued reference to FIGS. 1A-1D, the folding knife 1 can be put together by its user in the following manner. First, the plate 11B is placed at a specific angle with respect to the plate 11A such that the first aperture 112 corresponds to the first block 113 (see FIG. 1B). Then, the actuating portion 15 is rotated to bring the second block 151 to the orientation shown in FIG. 1B. After that, the first block 113 is inserted through the first aperture 112, and with the engaging block 1121 corresponding to the engaging groove 1111 of the pivotal connection post 111, the plate 11B is rotated so that the second aperture 114 corresponds to the second block 151. The second block 151 is then inserted through the second aperture 114, and with the other engaging block on the plate 11B corresponding to the engaging groove of the actuating portion 15, the actuating portion 15 is rotated again. Consequently, the first block 113 and the second block 151 no longer correspond to the first aperture 112 and the second aperture 114 respectively (see FIG. 1A), and the engaging block 1121 and the other engaging block of the plate 11B are respectively engaged with the blocks 113 and 151. By the same token, the first thing to be done to dismantle the folding knife 1 is to rotate the actuating portion 15 so that the second block 151 corresponds to the second aperture 114. Following that, the plate 11B is rotated until the first aperture 112 corresponds to the first block 113, and only then can the plate 11B and the blade 13 be sequentially detached, allowing individual components to be cleaned or the blade 13 to be replaced.
While the folding knife described above is configured to be disassembled and reassembled by its user, the following problems are expected to arise in practical use:
(1) When disassembling or reassembling the folding knife, the user must adjust the positions of the plates, the blocks, and the actuating portion by turns repeatedly, which complicates the disassembly and reassembly procedures greatly.
(2) With the blocks and the apertures having specific shapes, the user has to adjust the positions of the blocks and the apertures carefully, for each block cannot extend through the corresponding aperture unless the former corresponds to the latter. Positional adjustment of the blocks and the apertures, however, is extremely time-consuming.
(3) The thickness of each engaging block must be equal to or slightly smaller than the height of the corresponding engaging groove in order for each engaging block to engage with the corresponding block after the plate to be operated (i.e., the plate 11B) and the actuating portion are rotated. To this end, it is imperative to control the tolerances of the aforesaid thicknesses and heights within a very small range, or the folding knife will have problem being assembled (meaning the yield of the folding knife will be lowered).
(4) As the blocks are bound to collide respectively with the peripheries of the corresponding apertures when the user disassembles or reassembles the folding knife, the edges of the blocks or of the apertures may be damaged or deformed over time. Should the damage or deformation be severe, engagement between the blocks and their respective apertures will be made impossible, thus hampering normal use of the folding knife.
(5) While each block and the corresponding aperture must be adjusted to corresponding positions in order for the former to pass through the latter, it is difficult to align each block with the corresponding aperture when the folding knife is small, for in that case the blocks and the apertures will also be small. In other words, a reduction in size of the folding knife will add to the difficulty of assembly.
According to the above, the conventional folding knives still leave much to be desired. It is therefore a pressing issue for folding knife designers and manufacturers to develop a novel folding knife whose structural simplicity brings about greater convenience and safety of use.